If the Vikings defensive alignment looked a little odd at points last weekend, Jared Allen's neck spasms probably had something to do with it. Unable to turn his neck in one direction Sunday, Allen spent two snaps during the upset of San Francisco lining up at left end as opposed to his usual home on the right side.

But that's not an experiment the Vikings plan to continue.

Said defensive coordinator Alan Williams: "I think guys should do what they do best. He's been on the right side, and that's where he rushes from. Let the left tackle handle our best guy from the left side. I think you do what you do and don't try to outsmart yourself or out-trick yourself."

Williams said the suggestion to move Allen across the line came from the players, with defensive line coach Brendan Daly signing off on the idea.

"It just worked out that we have some older vets that can problem-solve on the sideline," Williams said. "That's a good thing, when they can come to you with a problem and an answer."

Added Allen: "[I was] a little bit of a fish out of water. I forget how to play that side. That used to be the only side I played until I got to the NFL."

For what it's worth, Allen picked up his first sack of the season from his usual spot at right end late in the game. He also forced a fumble on the play.

Allen has been limited in practice this week but says his neck pain is fading.

"A lot better," Allen said. "It's just one of those things -- you wake up on the wrong side of the pillow and it's just knotted up and locked up and it just wouldn't go down. But I did all my treatments this week and now I'm ready to rock."

No more rust

Running back Adrian Peterson says he's not quite back to 100 percent from last December's reconstructive knee surgery but hopes he will be at full strength soon.

"It'll just be me knowing my body," Peterson said. "When I look in the mirror, obviously my right leg is bigger than my left. And I know [my left leg] is not as strong as far as the different things I can do. That's when I'll be able to tell, when I won't be able to tell the difference between the strength in my legs."

Peterson carried the ball 25 times for 86 yards in Sunday's victory. For the season, he has 58 carries for 230 yards.

Asked if he feels he's still a bit rusty, Peterson said: "To be honest with you, I think the rust just got knocked off against San Fran. ... The previous two weeks, I woke up on Monday and my body felt great; a little soreness in my knee. I woke up Monday after this game and I felt like I played some football. I feel [the rust] is knocked off now. And that's what I needed."

Injury update

Linebacker Erin Henderson missed practice again Thursday, still awaiting clearance after suffering a concussion late in the Vikings' Week 2 loss to Indianapolis. Coach Leslie Frazier said he's still considering playing Henderson on Sunday if the veteran linebacker can get cleared and return to practice Friday.

Tight end Kyle Rudolph, meanwhile, returned to practice and was a limited participant after sitting out Wednesday because of a thigh bruise. Quarterback Christian Ponder was also listed as a limited participant because of a minor neck injury.

Reisner waived

The Vikings waived tight end Allen Reisner, a move made to clear a roster spot for Jerome Simpson. Simpson is returning to action this week after serving a three-game NFL suspension. The Vikings were allowed to keep 54 players on their active roster from Monday until Thursday afternoon but waived Reisner before the 3 p.m. deadline.

If Reisner clears waivers, there's a chance he could eventually be brought back to the practice squad.